Reference

Schumacher, B. A. and Martin, J. E. 2015. Polycotylus latipinnis Cope (Plesiosauria, Polycotylidae), a nearly complete skeleton from the Niobrara Formation (Early Campanian) of southwestern South Dakota, Journal of Vertebrate Paleontology, DOI: 10.1080/02724634.2015.1031341